The present invention relates to novel catalyst compositions suitable for use in preparing polyketones.
It is known to produce polyketones, which are linear alternating polymers of (a) one or more olefins and (b) carbon monoxide, by a liquid phase process in which the olefin(s) and carbon monoxide are polymerised together in methanol, ethanol or propanol solvent in the presence of a palladium catalyst. Such a process, which is disclosed in more detail in for example EP 121965 and EP 314309, typically employs a catalyst derived from (a) a palladium compound (b) a source of an anion which is either non-coordinating or only weakly coordinating to palladium and (c) a bisphosphine of formula R.sup.1 R.sup.2 P-R-PR.sup.3 R.sup.4 where R.sup.1 to R.sup.4 are independently aryl groups which can optionally be polar substituted and R is a divalent organic bridging group such as--(CH.sub.2)n--(n=2 to 6). The source of the anion is typically its conjugate acid.
It is furthermore known from EP-A-246683 that polyketones can also be prepared if component (b) in the catalyst is replaced by tin chloride or germanium chloride. Such salts of a strong acid and a weak base are electron acceptors, and thus "Lewis" acids.
EP-A-508502 discloses catalyst compositions comprising:
a) a Group VIII metal compound, PA1 b) a Lewis acid of the general formula MF.sub.n in which M represents an element that can form a Lewis acid with fluorine, F represents fluorine and n has the value 3 or 5, and PA1 c) a dentate ligand containing at least two phosphorus-, nitrogen- or sulphur-containing dentate groups through which the dentate ligand can complex with the Group VIII metal. PA1 (a) Group VIII metal compound, containing at least one ligand capable of coordinating to the Group VIII metal and PA1 (b) a boron hydrocarbyl compound preferably a Lewis acid of the formula BXYZ where at least one of X Y and Z is a monovalent hydrocarbyl group.
A problem with the prior art catalyst compositions is to improve their reaction rate.
It has now been found that high reaction rates can be obtained using catalyst compositions based upon Group VIII metal compounds in conjunction with specific boron compounds.